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(11) | EP 0 239 286 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Photonic switching |
| (57) A method and apparatus are disclosed for implementing an optical communication network
wherein switchable information signals are retained in the optical mode. Sources of
optical signals (291), destinations for optical signals (290), and intermediate photonic
switches (200) are interconnected by optical links (13), each link comprising two
unidirectional transmission optical fibers (135, 13N). An optical bit stream generated
at a source of optical signals comprises repetitive time frames (3005). Each time
frame includes a frame synchronizing signal (3001) and a plurality of signal groups
of information bits (3003) separated in time by a route switching interval (3014).
The optical bit streams entering a photonic switch are frame synchronized. A particular
group of information bits retains its position in time within a frame from the source
of the optical signal to its destination. The photonic switch is set up (234) during
a route switching interval for transmission of a group of information bits from an
input to an output of the photonic switch. Advantageously, in such a network optical
signals need not be converted to electrical signals as they traverse communication
links from a source to a destination. |